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Difficult Decisions Made Easier

NASA missions are extremely complex and prone to sudden, catastrophic failure if equipment falters or if an unforeseen event occurs. For these reasons, NASA trains to expect the unexpected. It tests its equipment and systems in extreme conditions, and it develops risk-analysis tests to foresee any possible problems.

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Extension of Liouville Formalism to Postinstability Dynamics

A fictitious stabilizing force is introduced. A mathematical formalism has been developed for predicting the postinstability motions of a dynamic system governed by a system of nonlinear equations and subject to initial conditions. Previously, there was no general method for prediction and mathematical modeling of postinstability behaviors (e.g., chaos and turbulence) in such a system.

Posted in: Briefs, TSP

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Device for Automated Cutting and Transfer of Plant Shoots

This device is simple yet effective. A device that enables the automated cutting and transfer of plant shoots is undergoing development for use in the propagation of plants in a nursery or laboratory. At present, it is standard practice for a human technician to use a knife and forceps to cut, separate, and grasp a plant shoot. The great advantage offered by the present device is that its design and operation are simpler than would be those of a device based on the manual cutting/separation/grasping procedure. [The present device should not be confused with a prior device developed for partly the same purpose and described in "Compliant Gripper for a Robotic Manipulator" (NPO-21104), NASA Tech Briefs, Vol. 27, No. 3 (March 2003), page 59.]

Posted in: Briefs, TSP

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Neutral-Axis Springs for Thin-Wall Integral Boom Hinges

A document proposes the use of neutral-axis springs to augment the unfolding torques of hinges that are integral parts of thin-wall composite-material booms used to deploy scientific instruments from spacecraft. A spring according to the proposal would most likely be made of metal and could be either flat or curved in the manner of a measuring tape. Under the unfolded, straight-boom condition, each spring would lie along the neutral axis of a boom. The spring would be connected to the boom by two supports at fixed locations on the boom. The spring would be fixed to one of the supports and would be free to slide through the other support. The width, thickness, and material of the spring would be chosen to tailor the spring stiffness to provide the desired torque margin to assist in deployment of the boom. The spring would also contribute to the stiffness of the boom against bending and torsion, and could contribute some damping that would help suppress unwanted vibrations caused by the deployment process or by external disturbances.

Posted in: Briefs, TSP

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Shields for Enhanced Protection Against High-Speed Debris

A report describes improvements over the conventional Whipple shield (two thin, spaced aluminum walls) for protecting spacecraft against high-speed impacts of orbiting debris. The debris in question arise mainly from breakup of older spacecraft. The improved shields include exterior "bumper" layers composed of hybrid fabrics woven from combinations of ceramic fibers and high-density metallic wires or, alternatively, completely metallic outer layers composed of high-strength steel or copper wires. These shields are designed to be light in weight, yet capable of protecting against orbital debris with mass densities up to about 9 g/cm3, without generating damaging secondary debris particles. As yet another design option, improved shields can include sparsely distributed wires made of shape-memory metals that can be thermally activated from compact storage containers to form shields of predetermined shape upon arrival in orbit. The improved shields could also be used to augment shields installed previously.

Posted in: Briefs, TSP

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Scheduling Software for Complex Scenarios

Preparing a vehicle and its payload for a single launch is a complex process that involves thousands of operations. Because the equipment and facilities required to carry out these operations are extremely expensive and limited in number, optimal assignment and efficient use are critically important. Overlapping missions that compete for the same resources, ground rules, safety requirements, and the unique needs of processing vehicles and payloads destined for space impose numerous constraints that, when combined, require advanced scheduling.

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A Predictive Approach to Eliminating Errors in Software Code

NASA's Metrics Data Program Data Repository is a database that stores problem, product, and metrics data. The primary goal of this data repository is to provide project data to the software community. In doing so, the Metrics Data Program collects artifacts from a large NASA dataset, generates metrics on the artifacts, and then generates reports that are made available to the public at no cost. The data that are made available to general users have been sanitized and authorized for publication through the Metrics Data Program Web site by officials representing the projects from which the data originated.

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